ARM change name of defines for AT91 arm926ejs

Configuration defines should be preceeded with CONFIG_SYS_. Renamed
some at91 specific defines to conform to this naming convention:

AT91_CPU_NAME to CONFIG_SYS_AT91_CPU_NAME
AT91_MAIN_CLOCK to CONFIG_SYS_AT91_MAIN_CLOCK

Signed-off-by: Achim Ehrlich <aehrlich@taskit.de>
diff --git a/board/ronetix/pm9261/pm9261.c b/board/ronetix/pm9261/pm9261.c
index 6915b9b..8662339 100644
--- a/board/ronetix/pm9261/pm9261.c
+++ b/board/ronetix/pm9261/pm9261.c
@@ -189,7 +189,7 @@
 	lcd_printf ("(C) 2009 Ronetix GmbH\n");
 	lcd_printf ("support@ronetix.at\n");
 	lcd_printf ("%s CPU at %s MHz",
-		AT91_CPU_NAME,
+		CONFIG_SYS_AT91_CPU_NAME,
 		strmhz(temp, get_cpu_clk_rate()));
 
 	dram_size = 0;